WO2024237137A1 - Quantum dot composition, resin composition, and wavelength conversion material - Google Patents

Abstract

The present invention relates to a quantum dot composition containing quantum dots which fluoresce upon reception of excitation light, characterized in that the quantum dots each comprise a semiconductor nanoparticle core containing neither Cd nor Pb and a semiconductor nanoparticle shell, the surface of each quantum dot is coated with a metal oxide, and the quantum dot surface or metal oxide surface has been modified with a phosphonic acid derivative. Due to the configuration, provided is a quantum dot composition which, although including quantum dots of low toxicity, is inhibited from deteriorating in fluorescence efficiency.

Description

Quantum dot composition, resin composition, and wavelength conversion material

The present invention relates to a quantum dot composition, a resin composition, and a wavelength conversion material.

Quantum dots are semiconductor particles with nano-sized particle diameters. Excitons generated by light absorption are confined in nano-sized spaces, making the energy levels of the semiconductor nanoparticles discrete, and the band gap depends on the particle diameter. For this reason, quantum dots emit fluorescent light with high efficiency and have sharp emission spectra. In addition, because the band gap changes depending on the particle diameter, quantum dots have the advantage of being able to control the emission wavelength, and are expected to be used as wavelength conversion materials for solid-state lighting and displays (Patent Document 1).

Quantum dots that exhibit excellent fluorescent emission properties include those that contain Cd or Pb. However, because Cd and Pb are highly toxic to the human body and the environment, restrictions on their use are being considered around the world, including the European Union's RoHS Directive. For this reason, quantum dots that do not contain these toxic elements are being considered.

In addition, a method has been proposed for mounting quantum dots as a wavelength conversion material, in which quantum dots are dispersed in a resin material, and a resin composition containing the quantum dots is laminated onto a transparent film, thereby incorporating the quantum dots into a backlight unit as a wavelength conversion film (Patent Document 2).

However, quantum dots are easily destabilized due to their small nanometer particle size, large specific surface area, high surface energy, and surface activity. This makes them susceptible to surface defects due to dangling bonds and oxidation reactions on the quantum dot surface, which causes deterioration of the fluorescent emission properties. Currently available quantum dots have such stability problems, and are known to cause deterioration of their emission properties due to heat, humidity, photoexcitation, etc.

To prevent this deterioration, organic ligands called ligands are coordinated to the quantum dot surface after synthesis. The coordination of these ligands improves dispersibility in solvents and resins, and by passivating defects, it is possible to suppress deterioration in the fluorescence emission efficiency.

However, if an appropriate ligand is not selected for the quantum dot surface, the ligand may be detached from the quantum dot surface due to external influences such as heat or light exposure, resulting in a deterioration in the fluorescence emission efficiency.

The stability of quantum dots is an important issue, since changes in the fluorescence efficiency of quantum dots over time can lead to defects such as uneven color and light emission and dead dots when used in displays.

JP 2012-022028 A Special Publication No. 2013-544018 JP 2019-215516 A Patent No. 5900720 JP 2018-109141 A

In response to these problems, methods have been considered in which quantum dots are supported on inorganic oxides (Patent Document 3) and methods have been considered in which the stability of quantum dots is improved by using a gas barrier film with low oxygen and moisture permeability (Patent Document 4).

The method of supporting quantum dots on oxide prevents oxygen and water from coming into direct contact with the quantum dot surface, suppressing the oxidation reaction and thereby preventing deterioration of the fluorescence emission efficiency.

However, in methods such as the general sol-gel method, in which metal oxide precursors are reacted in a liquid phase at low temperatures, many hydroxyl groups remain on the oxide surface after the reaction. These surface hydroxyl groups form hydrogen bonds with water molecules in the air, forming a thin layer of adsorbed water on the nanometer order, a hydration layer, on the oxide surface.

It is difficult to completely remove the hydroxyl groups on the oxide surface by heating, and when a composition in which quantum dots are supported on an oxide is used as a wavelength conversion material, it is used in an environment where it is exposed to light and heat for long periods of time. As a result, the adsorbed water penetrates from the oxide surface to the inside, gradually progressing the oxidation reaction on the quantum dot surface and deteriorating the fluorescence emission efficiency.

Stabilization using a barrier film also poses the problem of deterioration due to the diffusion of oxygen and water vapor from the film's edges.

Furthermore, for mobile applications such as tablets and smartphones, there is a demand for thinner wavelength conversion films, but barrier films are generally around 20 to 200 μm thick, and in order to protect both sides of the film, the thickness must be at least 40 μm or more, which places a limit on how thin the wavelength conversion film can be.

Furthermore, a method has been proposed in which quantum dots are used not as a wavelength conversion film but as a color filter to directly convert blue excitation light into green and red (Patent Document 5). When using quantum dots as a color filter, it is not possible to use a barrier film, as in the wavelength conversion film described above, and the deterioration of the fluorescence emission efficiency of the quantum dots due to hardening of the quantum dot composition, subsequent manufacturing processes, and long-term use becomes a major problem.

Quantum dots that do not contain toxic elements are being investigated, but degradation of the fluorescence emission efficiency is an issue.

The present invention has been made to solve the above problems, and aims to provide a quantum dot composition that suppresses the deterioration of fluorescence emission efficiency even when low-toxicity quantum dots are used, a resin composition containing the quantum dot composition, and a wavelength conversion material.

The present invention has been made to achieve the above object, and provides a quantum dot composition containing quantum dots that emit fluorescence when excited by excitation light, the quantum dots being composed of a semiconductor nanoparticle core and a semiconductor nanoparticle shell that do not contain Cd or Pb, the quantum dot surface being coated with a metal oxide, and the quantum dot surface or the metal oxide surface being modified with a phosphonic acid derivative.

Such a quantum dot composition suppresses the deterioration of the fluorescence emission efficiency even when it is composed of quantum dots with low toxicity.

In this case, it is preferable that the quantum dot is composed of the semiconductor nanoparticle core and a single or multiple semiconductor nanoparticle shells covering the semiconductor nanoparticle core.

Such a quantum dot composition would be preferable in terms of fluorescence emission properties and stability.

In this case, it is preferable that the semiconductor nanoparticle core is selected from ZnS, ZnSe, ZnTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, _InSb , _AgGaS2 , _AgInS2 , _AgGaSe2 , _AgInSe2 , _CuGaS2 , CuGaSe2, _CuInS2 , _CuInSe2 , _ZnSiP2 , and _ZnGeP2 as a single crystal, multiple crystals, or mixed crystals.

Such a quantum dot composition would be preferable in terms of fluorescence emission properties and stability.

At this time, the semiconductor nanoparticle core surface is composed of GaCl ₃ , GaI ₃ , GaBr ₃ , ZnCl ₂ , ZnBr ₂ , ZnI ₂ , InCl ₃ , InBr ₃ , InI ₃ , AgCl, AgBr, AgI, KCl, KBr, KI, _NaCl , NaBr, NaI, MgCl ₂ , MgBr ₂ , MgI ₂ , CaCl 2 , CaBr ₂ , CaI ₂ , MnCl ₂ , MnBr ₂ , MnI ₂ , FeCl ₂ , FeBr ₂ , FeI ₂ , CuCl ₂ , CuBr ₂ , CuI ₂ , ZrCl ₄ , ZrBr ₄ , ZrI ₄ , GeCl ₄ , GeBr ₄ , and GeI ₄ .

Such a quantum dot composition would be preferable in terms of fluorescence emission properties and stability.

In this case, it is preferable that the semiconductor nanoparticle shell is selected from ZnS, ZnSe, ZnTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, and InSb as a single crystal, multiple crystals, or mixed crystals.

Such a quantum dot composition would be preferable in terms of improving the fluorescence emission efficiency and stability.

In this case, it is preferable that the metal oxide is at least one compound selected _{from TiO2} , _ZnO , _Al2O3 , _SiO2 , _ZrO2 , _Fe2O3 , _MgO , _Y2O3 , _HfO2 , _CeO2 , _In2O3 , _SnO2 , _WO3 , _CrO3 , _Ta2O3 , _BaTiO3 , _V2O5 , _NiO , _NbO , _Cu2O , CuO _, and _MoO3 .

Such a quantum dot composition would be preferable in terms of improving the fluorescence emission efficiency and stability.

（式（Ｉ）中、Ｒ_１は１つ以上の炭素原子を有する１価の有機基である。） In this case, the phosphonic acid derivative is preferably represented by the following formula (I).

(In formula (I), R ₁ is a monovalent organic group having one or more carbon atoms.)

Such a quantum dot composition suppresses the deterioration of the fluorescence emission efficiency and improves stability.

In this case, the phosphonic acid derivative is 3-phenyl-2-propenylphosphonic acid, tenofovir, 2-phosphonobutane-1,2,4-tricarboxylic acid, 4-phosphonobenzoic acid, vinylphosphonic acid, n-octylphosphonic acid, (3-bromopropyl)phosphonic acid, (4-bromobutyl)phosphonic acid, (2-bromoethyl)phosphonic acid, (4-bromophenyl)phosphonic acid, 3-phosphonopropionic acid, (4-hydroxyphenyl)phosphonic acid, heptylphosphonic acid, xylphosphonic acid, 4-phosphonobutyric acid, propylphosphonic acid, (4-aminobenzyl)phosphonic acid, (4-aminophenyl)phosphonic acid, 3-phosphonobenzoic acid, methylphosphonic acid, nonylphosphonic acid, benzhydrylphosphonic acid, octadecylphosphonic acid, (aminomethyl)phosphonic acid, (2-phenylethyl)phosphonic acid, ethylphosphonic acid, butylphosphonic acid, decylphosphonic acid, dodecylphosphonic acid, (2-chloroethyl)phosphonic acid, 4-Methoxyphenylphosphonic acid, hexadecylphosphonic acid, (4-hydroxybenzyl)phosphonic acid, phenylphosphonic acid, (1H,1H,2H,2H-heptadecafluorodecyl)phosphonic acid, tetradecylphosphonic acid, (1-aminoethyl)phosphonic acid, undecylphosphonic acid, heptylphosphonic acid, 10-carboxydecylphosphonic acid, 11-aminoundecylphosphonic acid hydrobromide, 11-hydroxyundecylphosphonic acid, 1H It is preferable that the compound is one or more selected from the group consisting of 1H,2H,2H-perfluoro-n-hexylphosphonic acid, 1H,1H,2H,2H-perfluorooctylphosphonic acid, 1H,1H,2H,2H-perfluoro-n-decylphosphonic acid, 11-{2-[2-(2-methoxyethoxy)ethoxy]ethoxy}undecylphosphonic acid, 12-mercaptodecylphosphonic acid, and [11-(acryloyloxy)undecyl]phosphonic acid.

Such phosphonic acid derivatives can be used in the quantum dot composition of the present invention, which suppresses deterioration of the fluorescence emission efficiency and improves stability.

（式（ＩＩ）中、Ｒ_２は１つ以上の炭素原子を有する２価の有機基である。） In this case, the phosphonic acid derivative is preferably represented by the following formula (II):

(In formula (II), _R2 is a divalent organic group having one or more carbon atoms.)

Such a quantum dot composition suppresses the deterioration of the fluorescence emission efficiency and improves stability.

In this case, it is preferable that the phosphonic acid derivative is one or more selected from m-xylylene diphosphonic acid, o-xylylene diphosphonic acid, methylene diphosphonic acid, alendronic acid, 1,4-butylene diphosphonic acid, glycine-N,N-bis(methylenephosphonic acid), p-xylylene diphosphonic acid, zoledronic acid, 1,3-propylene diphosphonic acid, 1,5-pentylene diphosphonic acid, 1,4-phenylene diphosphonic acid, 1,2-ethylene diphosphonic acid, 1,6-hexylene diphosphonic acid, minodronate, and 1-hydroxyethane-1,1-diphosphonic acid.

Such phosphonic acid derivatives can be used in the quantum dot composition of the present invention.

（式（ＩＩＩ）中、Ｒ_３は１つ以上の炭素原子を有する３価の有機基である。） In this case, the phosphonic acid derivative is preferably represented by the following formula (III).

(In formula (III), _R3 is a trivalent organic group having one or more carbon atoms.)

Such a quantum dot composition suppresses the deterioration of the fluorescence emission efficiency and improves stability.

In this case, it is preferable that the phosphonic acid derivative is nitrilotris(methylene phosphonic acid).

Such phosphonic acid derivatives can be used in the quantum dot composition of the present invention.

（式（ＩＶ）中、Ｒ_４は１つ以上の炭素原子を有する２価の有機基である。） In this case, the phosphonic acid derivative is preferably represented by the following formula (IV).

(In formula (IV), _R4 is a divalent organic group having one or more carbon atoms.)

Such a quantum dot composition suppresses the deterioration of the fluorescence emission efficiency and improves stability.

In this case, it is preferable that the phosphonic acid derivative is N,N,N',N'-ethylenediaminetetrakis(methylenephosphonic acid).

Such phosphonic acid derivatives can be used in the quantum dot composition of the present invention.

In this case, it is preferable that _R1 contains at least one of a linear or branched alkyl group having one or more carbon atoms, a linear or branched alkylene group having one or more carbon atoms, an amino group, a carboxylic acid group, an ethoxy group, a bromo group, a chloro group, a phenol group, a perfluoroalkyl group, a hydroxyl group, a phenyl group, a thiol group, an acryloyl group, and an oligoethylene glycol group.

Such phosphonic acid derivatives can be used in the quantum dot composition of the present invention.

In this case, it is preferable that _R2 contains at least one of a linear or branched alkyl group having one or more carbon atoms, a linear or branched alkylene group having one or more carbon atoms, an amino group, a carboxylic acid group, an ethoxy group, a bromo group, a chloro group, a phenol group, a perfluoroalkyl group, a hydroxyl group, a phenyl group, a thiol group, an acryloyl group, and an oligoethylene glycol group.

Such phosphonic acid derivatives can be used in the quantum dot composition of the present invention.

In this case, it is preferable that _R3 contains at least one of a linear or branched alkyl group having one or more carbon atoms, a linear or branched alkylene group having one or more carbon atoms, an amino group, a carboxylic acid group, an ethoxy group, a bromo group, a chloro group, a phenol group, a perfluoroalkyl group, a hydroxyl group, a phenyl group, a thiol group, an acryloyl group, and an oligoethylene glycol group.

Such phosphonic acid derivatives can be used in the quantum dot composition of the present invention.

In this case, it is preferable that _R4 contains at least one of a linear or branched alkyl group having one or more carbon atoms, a linear or branched alkylene group having one or more carbon atoms, an amino group, a carboxylic acid group, an ethoxy group, a bromo group, a chloro group, a phenol group, a perfluoroalkyl group, a hydroxyl group, a phenyl group, a thiol group, an acryloyl group, and an oligoethylene glycol group.

Such phosphonic acid derivatives can be used in the quantum dot composition of the present invention.

The present invention also provides a resin composition in which the quantum dot composition described above is dispersed in a resin.

Such a resin composition is one in which the deterioration of the fluorescent light emission efficiency is suppressed.

In this case, it is preferable that the resin is at least one selected from the group consisting of epoxy resins, acrylic resins, fluorine resins, silicone resins, carbonate resins, and glass resins.

Such resins can be used in the resin composition of the present invention.

The present invention also provides a wavelength converting material that contains a cured product of the resin composition described above.

Such wavelength conversion materials suppress deterioration of the fluorescence emission efficiency and improve reliability.

As described above, the quantum dot composition of the present invention, the resin composition containing the quantum dot composition, and the wavelength conversion material suppress deterioration of the fluorescence emission efficiency even when low-toxicity quantum dots are used.

The present invention is described in detail below, but is not limited to these.

As mentioned above, there was a need for a quantum dot composition that would suppress the deterioration of fluorescence emission efficiency even when using quantum dots with low toxicity.

As a result of intensive research into the above-mentioned problems, the inventors have discovered that a quantum dot composition containing quantum dots that emit fluorescence when excited by excitation light, the quantum dots being composed of a semiconductor nanoparticle core and a semiconductor nanoparticle shell that do not contain Cd or Pb, the quantum dot surfaces being coated with a metal oxide, and the quantum dot surfaces or the metal oxide surfaces being modified with a phosphonic acid derivative, can suppress deterioration in fluorescence emission efficiency even when low-toxicity quantum dots are used, and have completed the present invention.

As described above, there is a need for a resin composition containing a quantum dot composition that suppresses the deterioration of fluorescence emission efficiency even when low-toxicity quantum dots are used.

As a result of extensive research into the above-mentioned problems, the inventors discovered that a resin composition in which the quantum dot composition described above is dispersed in a resin can suppress the deterioration of fluorescence emission efficiency even when low-toxicity quantum dots are used, and thus completed the present invention.

Furthermore, as mentioned above, there was a demand for wavelength conversion materials that use low-toxicity quantum dots and that suppress deterioration of fluorescence emission efficiency.

As a result of extensive research into the above-mentioned problems, the inventors discovered that a wavelength conversion material containing a cured product of the resin composition described above can suppress the deterioration of fluorescence emission efficiency even when low-toxicity quantum dots are used, and thus completed the present invention.

The following describes an embodiment of the present invention. However, in the present invention, the composition, type, and manufacturing method of the quantum dots, metal oxide, and phosphonic acid derivative are not limited to the following forms.

In other words, the present invention is a quantum dot composition containing quantum dots that emit fluorescence when exposed to excitation light, the quantum dots being composed of a semiconductor nanoparticle core and a semiconductor nanoparticle shell that do not contain Cd or Pb, the quantum dot surfaces being coated with a metal oxide, and the quantum dot surfaces or the metal oxide surfaces being modified with a phosphonic acid derivative.

[Quantum dots]
The structure of the quantum dot in the present invention is not particularly limited as long as it is composed of a semiconductor nanoparticle core and a semiconductor nanoparticle shell. Such quantum dots have excellent fluorescence emission properties and stability. For example, in a semiconductor nanoparticle having a core/shell structure in which a nano-sized semiconductor particle is used as the core and a semiconductor particle having a larger band gap and lower lattice mismatch than the core is used as the shell, the excitons generated in the shell are confined inside the core particle, improving the fluorescence emission efficiency, and further improving the stability since the core surface is covered with the shell.

It is also preferable that the quantum dots are composed of a semiconductor nanoparticle core and a single or multiple semiconductor nanoparticle shells covering the semiconductor nanoparticle core. With such a quantum dot composition, the deterioration of the fluorescence emission efficiency is further suppressed.

The material for the semiconductor nanoparticle core of the core/shell semiconductor nanoparticle is not particularly limited as long as it does not contain the elements Cd or Pb from the viewpoint of toxicity, but for example, a material selected from the group consisting of II-VI compounds, III-V compounds, I-III-VI compounds, II-IV-V compounds, and alloys or mixed crystals thereof can be used.

Specifically, the material of the semiconductor nanoparticle core may be selected from ZnS, ZnSe, ZnTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, _InSb , _AgGaS2 , _AgInS2 , _AgGaSe2 , AgInSe2, _CuGaS2 , _CuGaSe2 , _CuInS2 , _CuInSe2 , _ZnSiP2 , and ZnGeP2 in a single, multiple, or mixed crystal form. Of these materials, ZnSe, ZnTe, and _InP are particularly preferred in terms of fluorescence emission properties and stability.

In addition, the surface of the core particle of the core/shell semiconductor nanoparticles is preferably passivated with an inorganic compound. This inactivates defects on the surface of the core particle, improving the fluorescence emission efficiency and suppressing deterioration of the fluorescence emission efficiency over time.

The inorganic compound for passivation is not particularly limited, but examples thereof include metal halides, and from the viewpoint of improving the fluorescence emission efficiency, _GaCl3 , _GaI3 , GaBr3, _ZnCl2 , _ZnBr2 , _ZnI2 , _InCl3 , _InBr3 , _InI3 , AgCl, AgBr _, AgI, KCl, KBr, KI, NaCl, NaBr, NaI, MgCl2, _MgBr2 , _MgI2 , _CaCl2 , _CaBr2 , _CaI2 , _MnCl2 , _MnBr2 , _MnI2 , _FeCl2 , _FeBr2 , _FeI2 , _CuCl2 , _CuBr2 , _CuI2 , _ZrCl4 , _ZrBr , Particularly preferred is at least one compound selected from ZrI ₄ , GeCl ₄ , _{GeBr 4} and GeI ₄ .

The material for the shell of the semiconductor nanoparticle is not particularly limited as long as it does not contain the elements Cd or Pb from the viewpoint of toxicity, but it is preferable that it has a large band gap and low lattice mismatch with the core material, and can be selected from the group consisting of alloys and mixed crystals of II-VI and III-V compounds.

Specific shell materials may be selected from ZnS, ZnSe, ZnTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, and InSb, either singly, in multiple, or as mixed crystals. Of these materials, ZnSe and ZnS are particularly preferred in terms of improved fluorescence emission efficiency and stability.

There are various methods for producing semiconductor nanoparticles, such as liquid phase methods and gas phase methods, but the present invention is not particularly limited to these. From the viewpoint of exhibiting high fluorescence emission efficiency, it is preferable to use semiconductor nanoparticles obtained using the hot soap method or hot injection method, in which precursor species are reacted at high temperature in a non-polar solvent with a high boiling point.

In addition, to reduce surface defects during and after synthesis, it is preferable that the quantum dots have organic ligands, called ligands, coordinated to their surfaces.

The ligand preferably contains an aliphatic hydrocarbon from the viewpoint of suppressing aggregation of the quantum dots. Examples of such ligands include oleic acid, stearic acid, palmitic acid, myristic acid, lauric acid, decanoic acid, octanoic acid, oleylamine, stearyl (octadecyl)amine, dodecyl (lauryl)amine, decylamine, octylamine, octadecanethiol, hexadecanethiol, tetradecanethiol, dodecanethiol, decanethiol, octanethiol, trioctylphosphine, trioctylphosphine oxide, triphenylphosphine, triphenylphosphine oxide, tributylphosphine, and tributylphosphine oxide, and these may be used alone or in combination.

[Surface coating of quantum dots with metal oxide]
The quantum dots of the present invention have a surface coated with a metal oxide, which prevents oxygen and water in the air from coming into direct contact with the quantum dot surface and inhibits oxidation reactions, thereby preventing deterioration of the fluorescence emission efficiency.

In the present invention, the "coating" of the quantum dot surface with metal oxide may be in the form of partial or complete coating, so long as the deterioration of the fluorescence emission efficiency over time is suppressed. In addition, it may be a uniform coating layer such as a core-shell structure, or a non-uniform coating layer, and may be a structure in which multiple semiconductor nanoparticles are coated with metal oxide. The film thickness of the metal oxide is not particularly limited, but is preferably 200 nm or less from the viewpoint of translucency.

In the present invention, the type of the oxide coating layer is not particularly limited, but _may be at _{least one compound selected from TiO2, ZnO, Al2O3, SiO2, ZrO2, Fe2O3, MgO, Y2O3, HfO2, CeO2, In2O3, SnO2, WO3 , CrO3 , Ta2O3 , BaTiO3 , V2O5 , NiO , NbO , Cu2O , CuO ,} and _MoO3 . _From the viewpoint of improving the stability of _{the quantum} dots, _TiO2 , _Al2O3 , _SiO2 , _{and ZrO2} are more preferable.

The method for forming the metal oxide coating layer is not particularly limited, but from the viewpoint of selectively progressing the reaction on the quantum dot surface, a method in which a metal oxide precursor is reacted in a liquid phase is preferred.

In the present invention, one example is a method for forming an oxide coating layer using microwave treatment. By using microwaves, the metal oxide precursor is heated directly from the inside, allowing the reaction to proceed selectively in a shorter time, forming an oxide layer on the quantum dot surface.

Here, "microwaves" generally refer to electromagnetic waves with a frequency of 300 MHz to 3 THz. In addition, examples of methods for irradiating microwaves include, but are not limited to, a method using flexiWAVE manufactured by Milestone General.

In this coating process, it is preferable to coat the surface of the semiconductor nanoparticles with metal oxide by performing a microwave irradiation treatment on the coexisting metal oxide precursor and quantum dots and a metal oxide precursor in the coexistence. This allows the efficient formation of a metal oxide coating layer, and suppresses the deterioration of the fluorescence emission efficiency.

In this case, it is preferable to select one or more of a polar solvent, a non-polar solvent, and an ionic liquid as the dispersion medium for the quantum dots and the metal oxide precursor, and form the coating layer in that solvent.

In addition, it is preferable that the solvent used in this coating step is one or more of toluene, hexane, cyclohexane, benzene, and diethyl ether. These non-polar solvents can further improve the dispersibility of the semiconductor nanoparticles.

If the solvent is non-polar, a heating element that absorbs microwaves, such as Milestone's Weflon, a type of PTFE resin containing carbon components, may be used during the coating process.

The precursor of the metal oxide is not particularly limited, but it is preferable to use one or more selected from metal alkoxides, metal halides, and metal complexes. From the viewpoint of stability, silicon alkoxides, aluminum alkoxides, zirconium alkoxides, and titanium alkoxides are particularly preferable as the metal oxide precursor.

In this case, it is preferable to use a catalyst to promote the reaction of the metal oxide precursor during the coating process. In particular, when a metal alkoxide is used, it is desirable to use a catalyst to promote the sol-gel reaction. Examples of catalysts include acidic aqueous solutions and basic aqueous solutions, and basic aqueous solutions are particularly preferable from the viewpoint of the film thickness of the coating layer.

Furthermore, from the viewpoint of dispersibility of the metal oxide precursor during the coating process, a surfactant may be added. The surfactant is not particularly limited, but examples include quaternary ammonium salts such as cetyltrimethylammonium bromide, which are cationic surfactants; carboxylates and sulfonates, which are anionic surfactants; and polyoxyethylene alkyl ethers and cetyltrimethylammonium bromide, which are nonionic surfactants. Cationic surfactants are particularly preferred from the viewpoint of dispersibility of the metal oxide precursor.

It is also preferable to carry out the coating process in the presence of alcohol. If coating is carried out in the presence of alcohol, the dispersibility of the metal oxide precursor is better. Also, if a surfactant is added, dispersibility can be further improved by dissolving it in a polar solvent such as alcohol.

The reaction temperature during microwave irradiation treatment varies depending on the solvent, but is preferably 40 to 200°C, more preferably 50 to 110°C, from the viewpoint of preventing deterioration of the fluorescence emission efficiency.

As an example of the oxide coating process in this embodiment, microwave treatment is used, but there are no particular limitations as long as the quantum dot surface is "coated" with an oxide layer.

[Phosphonic acid derivatives]
As described above, in this embodiment, a metal oxide precursor is reacted in a solution to form a metal oxide coating layer on the surface of the quantum dots, thereby preventing water and oxygen in the air from directly contacting the quantum dot surface and suppressing deterioration of the fluorescence emission efficiency.

However, after the oxide coating layer is formed, many hydroxyl groups remain on the outer surface of the oxide. When these hydroxyl groups come into contact with water in the air, hydrogen bonds form a thin layer of adsorbed water on the oxide surface, a hydration layer, which is on the nanometer order of size.

When a composition in which the surface of quantum dots is coated with an oxide as described above is used as a wavelength conversion material, it is in an environment where it is exposed to external stimuli such as light and heat for a long period of time, so this adsorbed water gradually penetrates to the internal quantum dot surface, promoting surface oxidation and causing a deterioration in the fluorescence emission efficiency over long-term use. In order to suppress this deterioration in the fluorescence emission efficiency, it is preferable to remove as many hydroxyl groups as possible from the oxide surface.

However, it is difficult to completely remove the hydroxyl groups on the surface of this metal oxide by heating. Although this depends on the composition of the metal oxide, heating to approximately 500°C or higher is necessary. Heating at this temperature range changes the shape of the quantum dots and reduces or deactivates their luminescence efficiency, so it is difficult to remove the hydroxyl groups by heating alone.

The modifier useful in the present invention and necessary for removing hydroxyl groups on the oxide surface is a phosphonic acid derivative, and the quantum dot composition in this embodiment is composed of the quantum dots, an oxide that covers the quantum dot surface, and a phosphonic acid derivative that modifies the quantum dot surface or the oxide surface.

Phosphonic acid derivatives are stable compounds in themselves and do not self-polymerize, so they do not precipitate in the bulk and selectively adhere to and modify oxide surfaces or quantum dot surfaces.

In particular, on oxide surfaces, heat treatment at several tens of degrees causes a dehydration condensation reaction between the hydroxyl groups of the metal oxide and the phosphonic acid derivative, which removes the hydroxyl groups on the oxide surface and modifies the oxide surface with the phosphonic acid derivative.

Furthermore, since H ⁺ (protons) continue to be donated from the OH groups of the phosphonic acid derivative to the dangling oxygen bonds on the oxide surface, the above-mentioned dehydration condensation reaction is repeated, and the oxide surface is densely modified with the phosphonic acid derivative.

In this embodiment, "modification" refers to a state in which phosphonic acid is attached to a metal oxide surface or a quantum dot surface. The attachment of a phosphonic acid derivative to a surface by "modification" includes partial and full surface attachment, and refers to a state in which the phosphonic acid derivative is attached to at least a part of the surface.

The term "adhesion" as used above may refer to either physical adsorption or chemical bonding, and may broadly refer to, for example, covalent bonding, ionic bonding, or hydrogen bonding, or may refer to a combination of these.
As an example, the quantum dot composition comprising the quantum dots, the oxide coating layer, and the modification with a phosphonic acid derivative may be in a state in which the organic ligands attached to the metal oxide or quantum dot surface during synthesis coexist with the phosphonic acid derivative.

The type of phosphonic acid derivative is not particularly limited, but for example, the structure of this compound is preferably at least one of the following formulas (I), (II), (III), and (IV).

（式（Ｉ）中、Ｒ_１は１つ以上の炭素原子を有する１価の有機基である。）

(In formula (I), R ₁ is a monovalent organic group having one or more carbon atoms.)

（式（ＩＩ）中、Ｒ_２は１つ以上の炭素原子を有する２価の有機基である。）

(In formula (II), _R2 is a divalent organic group having one or more carbon atoms.)

（式（ＩＩＩ）中、Ｒ_３は１つ以上の炭素原子を有する３価の有機基である。）

(In formula (III), _R3 is a trivalent organic group having one or more carbon atoms.)

（式（ＩＶ）中、Ｒ_４は１つ以上の炭素原子を有する２価の有機基である。）

(In formula (IV), _R4 is a divalent organic group having one or more carbon atoms.)

In certain embodiments of the compounds of formulae (I) to (IV), R ₁ to R ₄ preferably include at least one of a linear or branched alkyl group having one or more carbon atoms, a linear or branched alkylene group having one or more carbon atoms, an amino group, a carboxylic acid group, an ethoxy group, a bromo group, a chloro group, a phenol group, a perfluoroalkyl group, a hydroxyl group, a phenyl group, a thiol group, an acryloyl group, and an oligoethylene glycol group.

Specific examples of the compound represented by formula (I) include 3-phenyl-2-propenylphosphonic acid, tenofovir, 2-phosphonobutane-1,2,4-tricarboxylic acid, 4-phosphonobenzoic acid, vinylphosphonic acid, n-octylphosphonic acid, (3-bromopropyl)phosphonic acid, (4-bromobutyl)phosphonic acid, (2-bromoethyl)phosphonic acid, (4-bromophenyl)phosphonic acid, 3-phosphonopropionic acid, (4-hydroxyphenyl)phosphonic acid, acid, hexylphosphonic acid, 4-phosphonobutyric acid, propylphosphonic acid, (4-aminobenzyl)phosphonic acid, (4-aminophenyl)phosphonic acid, 3-phosphonobenzoic acid, methylphosphonic acid, nonylphosphonic acid, benzhydrylphosphonic acid, octadecylphosphonic acid, (aminomethyl)phosphonic acid, (2-phenylethyl)phosphonic acid, ethylphosphonic acid, butylphosphonic acid, decylphosphonic acid, dodecylphosphonic acid, (2-chloroethyl)phosphonic acid (1H,1H,2H,2H-heptadecafluorodecyl)phosphonic acid, tetradecylphosphonic acid, (1-aminoethyl)phosphonic acid, undecylphosphonic acid, heptylphosphonic acid, 10-carboxydecylphosphonic acid, 11-aminoundecylphosphonic acid hydrobromide, 11-hydroxyphenylphosphonic acid ... These include undecylphosphonic acid, 1H,1H,2H,2H-perfluoro-n-hexylphosphonic acid, 1H,1H,2H,2H-perfluorooctylphosphonic acid, 1H,1H,2H,2H-perfluoro-n-decylphosphonic acid, 11-{2-[2-(2-methoxyethoxy)ethoxy]ethoxy}undecylphosphonic acid, 12-mercaptodecylphosphonic acid, and [11-(acryloyloxy)undecyl]phosphonic acid.

Specific examples of compounds of formula (II) include m-xylylenediphosphonic acid, o-xylylenediphosphonic acid, methylenediphosphonic acid, alendronic acid, 1,4-butylenediphosphonic acid, glycine-N,N-bis(methylenephosphonic acid), p-xylylenediphosphonic acid, zoledronic acid, 1,3-propylenediphosphonic acid, 1,5-pentylenediphosphonic acid, 1,4-phenylenediphosphonic acid, 1,2-ethylenediphosphonic acid, 1,6-hexylenediphosphonic acid, minodronate, and 1-hydroxyethane-1,1-diphosphonic acid.

Specific examples of formula (III) include nitrilotris(methylene phosphonic acid).

Specific examples of formula (IV) include N,N,N',N'-ethylenediaminetetrakis(methylenephosphonic acid).

The above phosphonic acid derivatives can be used alone or in combination of two or more.

The heating temperature when modifying the quantum dot surface or metal oxide surface with the above phosphonic acid derivative is not particularly limited, but in order to perform the modification efficiently, the heating temperature is preferably in the range of 50 to 300°C, and more preferably in the range of 80°C to 200°C. Within such a range, the quantum dot surface can be modified more efficiently.

The amount of the phosphonic acid derivative added as the surface modifier is not particularly limited as long as the phosphonic acid derivative modifies the quantum dot surface or metal oxide surface. For example, an amount of 30 wt% or less is preferable because it can suppress aggregation of the quantum dots and precipitation of the phosphonic acid derivative. An amount of 0.01 wt% or more can fully exert the effect of modifying the quantum dot surface or metal oxide surface. Therefore, the weight of the surface modifier added is preferably in the range of 0.01 to 30 wt% relative to the solid weight of the quantum dots, and more preferably in the range of 0.05 to 20 wt%.

Quantum dot composition
In a quantum dot composition in which the quantum dot surface is coated with the oxide layer and the quantum dot surface or the oxide layer surface is modified with phosphonic acid, the oxidation reaction on the quantum dot surface is suppressed, thereby suppressing deterioration in the fluorescence emission efficiency and improving stability.

[Resin composition]
The quantum dot composition can be used as a resin composition dispersed in a resin. The resin material is not particularly limited, but is preferably one in which the quantum dot composition does not aggregate or the fluorescence emission efficiency does not deteriorate, and examples thereof include at least one selected from epoxy resins, acrylic resins, fluorine resins, silicone resins, carbonate resins, and glass resins.

In order to increase the efficiency of fluorescent light emission, it is preferable that these resin compositions have high transmittance, and it is particularly preferable that the transmittance be 80% or more.

In addition, the concentration of quantum dots contained in the resin composition is not particularly limited, and can be appropriately adjusted according to the film thickness, the luminous efficiency of the quantum dots, and the characteristics of the desired wavelength conversion material.

In addition, the resin composition may contain substances other than the quantum dot composition, and may contain fine particles of silica, zirconia, alumina, titania, etc. as light scatterers, and may also contain inorganic or organic phosphors.

Examples of inorganic phosphors include YAG, LSN, LYSN, CASN, SCASN, KSF, CSO, β-SIALON, GIAG, LuAG, and SBCA, while examples of organic phosphors include perylene derivatives, anthraquinone derivatives, anthracene derivatives, phthalocyanine derivatives, cyanine derivatives, dioxazine derivatives, benzoxazinone derivatives, coumarin derivatives, quinophthalone derivatives, benzoxazole derivatives, and pyrarizone derivatives.

[Wavelength conversion material]
The present invention also provides a wavelength converting material containing the cured product of the resin composition. The wavelength converting material may be used as it is or may be processed. One form of the wavelength converting material is a wavelength conversion film in which the quantum dot composition is dispersed in the resin by processing the material into a sheet and then curing the sheet.

There are no particular limitations on the method for producing the wavelength conversion material, but for example, a resin composition in which a quantum dot composition is dispersed in a resin can be applied to a transparent film such as PET or polyimide, cured, and laminated to obtain the wavelength conversion material.

The transparent film can be coated using a spraying method such as spray or inkjet, or a spin coat, bar coater, or doctor blade method, and a resin layer is formed by coating. There are no particular limitations on the thickness of the resin layer and transparent film, and the thickness can be selected appropriately depending on the application. Such a wavelength conversion material suppresses deterioration of the fluorescent emission efficiency and improves reliability.

The present invention will be specifically explained below using manufacturing examples, examples, and comparative examples, but the present invention is not limited to these.

(Evaluation of Light Emitting Properties)
In the manufacturing examples, examples, and comparative examples, the fluorescence emission properties of the quantum dots, quantum dot compositions, and wavelength conversion materials were evaluated by measuring the fluorescence emission efficiency (internal quantum efficiency) at an excitation wavelength of 450 nm using a quantum efficiency measurement system (QE-2100) manufactured by Otsuka Electronics Co., Ltd.

(Quantum dot manufacturing)
(Production Example 1)
In a flask were placed 0.070 g (0.24 mmol) of indium acetate, 0.256 g (0.72 mmol) of palmitic acid, and 4.0 mL of 1-octadecene, which were then heated and stirred at 100° C. under reduced pressure to dissolve and degas for 1 hour.

After cooling the flask to room temperature, nitrogen was purged and 0.50 mL (0.17 mmol) of a 10 vol% (tris)trimethylsilylphosphine/octadecene solution was added to the flask. The flask was heated to 300°C and stirred for 20 minutes to synthesize InP semiconductor core particles.

Then, the flask was cooled to 200°C, after which 0.10 mL (0.02 mmol) of gallium(III) chloride/octadecene solution was added and heated for 30 minutes to passivate the surface of the InP semiconductor core particles.

Furthermore, after heating the flask to 240°C, 4.0 mL (1.2 mmol) of 0.30 M zinc stearate/octadecene solution was added and stirred for 30 minutes. Furthermore, 0.60 mL (0.90 mmol) of 1.5 M selenium/trioctylphosphine solution was added to the flask and stirred for 30 minutes.

Then, after cooling the flask to room temperature, 0.22 g (1.1 mmol) of zinc acetate was added, and the mixture was heated and stirred at 100°C under reduced pressure, and degassed for 1 hour while dissolving. After purging the flask with nitrogen, it was heated to 230°C, and 0.48 mL (2.0 mmol) of 1-dodecanethiol was added and stirred for 30 minutes.

The resulting solution was cooled to room temperature, ethanol was added, and the solution was centrifuged to precipitate quantum dots consisting of an InP core, a ZnSe shell, and a ZnS shell, and the supernatant was removed.

Toluene was then added to the precipitate to disperse it, ethanol was added again, the mixture was centrifuged, the supernatant was removed, and the precipitate was redispersed in toluene to prepare an InP/ZnSe/ZnS dispersion.

The resulting InP/ZnSe/ZnS toluene dispersion had a peak fluorescence wavelength of 535 nm and an internal quantum efficiency of 84%. In addition, the InP/ZnSe/ZnS toluene dispersion was irradiated with blue light of 450 nm wavelength using a blue LED light source (HL-36, manufactured by AS ONE Corporation) for 12 hours in an air atmosphere, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 68%.

(Production Example 2)
0.033 g (0.20 mmol) of silver acetate (I), 0.058 g (0.20 mmol) of indium acetate, 0.65 mL (2.7 mmol) of 1-dodecanethiol, and 4.0 mL of oleylamine were added to the flask, and the mixture was heated and stirred at 100° C. under reduced pressure and degassed for 1 hour. Nitrogen was then purged into the flask, and the mixture was heated to 200° C. and held for 20 minutes to synthesize AgInS ₂ semiconductor core particles.

Next, 0.014 g (0.1 mmol) of zinc chloride was dissolved in 1.0 ml of the trioctylphosphine solution and added to the flask heated to 200° C. to passivate the surfaces of the AgInS ₂ semiconductor core particles.

Then, the flask was heated to 230°C, and a 1.25M sulfur/trioctylphosphine solution was prepared, 1.0 mL of which was added to the reaction solution and stirred for 1 hour. Finally, a zinc precursor solution prepared by dissolving 0.099 g (0.54 mmol) of zinc acetate in 0.24 mL (0.76 mmol) of oleic acid and 0.15 mL of oleylamine was added to the flask, and the mixture was heated and stirred at 230°C for 1 hour.

The resulting solution was cooled to room temperature, ethanol was added, and the solution was centrifuged to precipitate the quantum dots and remove the supernatant. Toluene was then added to disperse the quantum dots, ethanol was added again, the solution was centrifuged, the supernatant was removed, and the precipitate was redispersed in toluene to prepare an AgInS ₂ /ZnS dispersion.

The resulting AgInS ₂ /ZnS toluene dispersion had a fluorescent emission wavelength peak of 599 nm and an internal quantum efficiency of 68%. The AgInS ₂ /ZnS dispersion was irradiated with blue light having a wavelength of 450 nm using a blue LED light source (HL-36, manufactured by AS ONE CORPORATION) for 12 hours in an air atmosphere, and then the fluorescent emission efficiency was measured, resulting in an internal quantum efficiency of 49%.

(Formation of Metal Oxide Coating Layer)
(Production Example 3)
10 g of the toluene solution of 1.0 wt % InP/ZnSe/ZnS quantum dots (semiconductor nanoparticles) obtained in Production Example 1, 110 μL of tetraethyl orthosilicate, 50 μL of 25% aqueous ammonia solution, and 0.010 g/100 μL of cetyltrimethylammonium bromide/ethanol solution were mixed and placed in a high-pressure reaction vessel.

Then, a _SiO2 coating layer was formed on the InP/ZnSe/ZnS surface by heating at 60°C for 5 minutes at 2450MHz using a microwave synthesis reaction device (flexi WAVE, manufactured by Milestone General Co., Ltd.). Ethanol was added to the obtained nanoparticles, which were then centrifuged to precipitate and remove the supernatant. Toluene or octadecene was added and the nanoparticles were redispersed by ultrasonic irradiation.

The resulting InP/ZnSe/ZnS/ _SiO2 toluene dispersion had an internal quantum efficiency of 81%. In addition, the InP/ZnSe/ZnS/ _SiO2 toluene dispersion was irradiated with blue light having a wavelength of 450 nm using a blue LED light source (HL-36, manufactured by AS ONE CORPORATION) for 12 hours in an air atmosphere, and then the fluorescence emission efficiency was measured. As a result, the internal quantum efficiency was 71%.

(Production Example 4)
10 g of the toluene solution of 1.0 wt % InP/ZnSe/ZnS quantum dots (semiconductor nanoparticles) obtained in Production Example 1, 0.10 g of aluminum isopropoxide, 50 μL of a 25% aqueous ammonia solution, and 0.010 g/100 μL of a cetyltrimethylammonium bromide/ethanol solution were mixed and placed in a high-pressure reaction vessel.

Then, an _Al2O3 coating layer was formed on the InP/ZnSe/ZnS surface by heating at 60°C for 5 minutes at 2450MHz using a microwave synthesis reaction device (flexi WAVE, manufactured by Milestone General Co., Ltd.). Ethanol was added to the obtained nanoparticles, which were then precipitated by centrifugation to remove the supernatant, and toluene or _octadecene was added and the nanoparticles were redispersed by ultrasonic irradiation.

The internal quantum efficiency of the obtained InP/ZnSe/ZnS/Al ₂ O ₃ toluene dispersion was 83%. In addition, the InP/ZnSe/ZnS/Al ₂ O ₃ toluene dispersion was irradiated with blue light having a wavelength of 450 nm using a blue LED light source (HL-36, manufactured by AS ONE CORPORATION) for 12 hours in an air atmosphere, and then the fluorescence emission efficiency was measured. As a result, the internal quantum efficiency was 72%.

(Production Example 5)
10 g of the toluene solution of 1.0 wt % InP/ZnSe/ZnS quantum dots (semiconductor nanoparticles) obtained in Production Example 1, 0.16 g of zirconium (IV) isopropoxide, 50 μL of a 25% aqueous ammonia solution, and 0.010 g/100 μL of a cetyltrimethylammonium bromide/ethanol solution were mixed and placed in a high-pressure reaction vessel.

Then, a _ZrO2 coating layer was formed on the InP/ZnSe/ZnS surface by heating at 60°C for 5 minutes at 2450MHz using a microwave synthesis reaction device (flexi WAVE, manufactured by Milestone General Co., Ltd.). Ethanol was added to the obtained nanoparticles, which were then precipitated by centrifugation to remove the supernatant, and toluene or octadecene was added and the nanoparticles were redispersed by ultrasonic irradiation.

The internal quantum efficiency of the obtained InP/ZnSe/ZnS/ _ZrO2 toluene dispersion was 83%. In addition, the InP/ZnSe/ZnS/ _ZrO2 toluene dispersion was irradiated with blue light having a wavelength of 450 nm using a blue LED light source (HL-36, manufactured by AS ONE CORPORATION) for 12 hours in an air atmosphere, and then the fluorescence emission efficiency was measured. As a result, the internal quantum efficiency was 73%.

(Production Example 6)
10 g of the toluene solution of 1.0 wt % InP/ZnSe/ZnS quantum dots (semiconductor nanoparticles) obtained in Production Example 1, 0.14 g of titanium tetraisopropoxide, 50 μL of a 25% aqueous ammonia solution, and 0.010 g/100 μL of a cetyltrimethylammonium bromide/ethanol solution were mixed and placed in a high-pressure reaction vessel.

Thereafter, a TiO ₂ coating layer was formed on the InP/ZnSe/ZnS surface by heating at 60° C. for 5 minutes at 2450 MHz using a microwave synthesis reaction apparatus (flexi WAVE, manufactured by Milestone General Co.).

Ethanol was added to the obtained nanoparticles, which were then precipitated by centrifugation to remove the supernatant, and the nanoparticles were redispersed by adding toluene or octadecene and subjecting them to ultrasonic irradiation.

The internal quantum efficiency of the obtained InP/ZnSe/ZnS/ _TiO2 toluene dispersion was 78%. In addition, the InP/ZnSe/ZnS/ _TiO2 toluene dispersion was irradiated with blue light having a wavelength of 450 nm using a blue LED light source (HL-36, manufactured by AS ONE CORPORATION) for 12 hours in an air atmosphere, and then the fluorescence emission efficiency was measured. As a result, the internal quantum efficiency was 70%.

(Production Example 7)
10 g of the toluene solution of 1.0 wt % AgInS ₂ /ZnS quantum dots (semiconductor nanoparticles) obtained in Production Example 2, 0.10 g of aluminum isopropoxide, 50 μL of 25% aqueous ammonia solution, and 0.010 g/100 μL of cetyltrimethylammonium bromide/ethanol solution were mixed and placed in a high-pressure reaction vessel.

Then, an Al ₂ O ₃ coating layer was formed on the AgInS ₂ /ZnS surface by heating at 60° C. for 5 minutes at 2450 MHz using a microwave synthesis reaction device (flexi WAVE, manufactured by Milestone General Co., Ltd.). Ethanol was added to the obtained nanoparticles, which were then precipitated by centrifugation to remove the supernatant, and toluene or octadecene was added and the nanoparticles were redispersed by ultrasonic irradiation.

The resulting AgInS ₂ /ZnS/Al ₂ O ₃ toluene dispersion had an internal quantum efficiency of 64%. The AgInS ₂ /ZnS/Al ₂ O ₃ toluene dispersion was irradiated with blue light having a wavelength of 450 nm using a blue LED light source (HL-36, manufactured by AS ONE CORPORATION) for 12 hours in an air atmosphere, and then the fluorescence emission efficiency was measured. The internal quantum efficiency was 54%.

(Production Example 8)
10 g of the toluene solution of 1.0 wt % AgInS ₂ /ZnS quantum dots (semiconductor nanoparticles) obtained in Preparation Example 2, 0.16 g of zirconium (IV) isopropoxide, 50 μL of 25% aqueous ammonia solution, and 0.010 g/100 μL of cetyltrimethylammonium bromide/ethanol solution were mixed and placed in a high-pressure reaction vessel.

Then, a _ZrO2 coating layer was formed on the _AgInS2 /ZnS surface by heating at 60°C for 5 minutes at 2450 MHz using a microwave synthesis reaction device (flexi WAVE, manufactured by Milestone General Co., Ltd.). Ethanol was added to the obtained nanoparticles, which were then precipitated by centrifugation to remove the supernatant, and toluene or octadecene was added and the nanoparticles were redispersed by ultrasonic irradiation.

The resulting AgInS ₂ /ZnS/ZrO ₂ toluene dispersion had an internal quantum efficiency of 63%. The AgInS ₂ /ZnS/ZrO ₂ toluene dispersion was irradiated with blue light having a wavelength of 450 nm using a blue LED light source (HL-36, manufactured by AS ONE CORPORATION) for 12 hours in an air atmosphere, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 53%.

(Surface Modification with Phosphonic Acid Derivatives)
Example 1
In a nitrogen atmosphere, 31 mg of hexadecylphosphonic acid (HDPA) was weighed into a 20 ml vial, and 5 ml of toluene and 1 ml of ethanol were added and stirred to prepare a hexadecylphosphonic acid solution.

Further, under a nitrogen atmosphere, 10 g of the 1.0 wt % InP/ZnSe/ZnS/SiO ₂ octadecene dispersion obtained in Production Example 3 and 6 ml of the hexadecylphosphonic acid solution were added to the three-neck flask.

The flask was then heated and stirred at 50° C. under reduced pressure for 10 minutes to degas the mixture. The flask was then purged with nitrogen, heated to 150° C., and stirred for 3 hours to obtain a quantum dot composition modified with HDPA for InP/ZnSe/ZnS/SiO _2. The resulting solution was cooled to room temperature, ethanol was added, and the mixture was centrifuged to precipitate the quantum dot composition and remove the supernatant.

Toluene was then added to the precipitate to disperse it, ethanol was added again, the mixture was centrifuged, the supernatant was removed, and the mixture was redispersed in toluene to prepare a toluene dispersion of the quantum dot composition.

The internal quantum efficiency of the obtained toluene dispersion of the quantum dot composition was 81%. In addition, the obtained toluene dispersion of the quantum dot composition was irradiated with blue light of 450 nm wavelength using a blue LED light source (HL-36, manufactured by AS ONE Corporation) for 12 hours in an air atmosphere, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 76%.

Example 2
In a nitrogen atmosphere, 31 mg of hexadecylphosphonic acid (HDPA) was weighed into a 20 ml vial, and 5 ml of toluene and 1 ml of ethanol were added and stirred to prepare a hexadecylphosphonic acid solution.

Further, under a nitrogen atmosphere, 10 g of the 1.0 wt % InP/ZnSe/ZnS/Al ₂ O ₃ octadecene dispersion obtained in Production Example 4 and 6 ml of the hexadecylphosphonic acid solution were added to the three-neck flask.

The flask was then heated and stirred at 50° C. under reduced pressure for 10 minutes to degas the mixture, then purged with nitrogen, heated to 150° C., and stirred for 3 hours to obtain a quantum dot composition modified with HDPA for InP/ZnSe/ZnS/Al ₂ O ₃ .

The resulting solution was cooled to room temperature, ethanol was added, and the solution was centrifuged to precipitate the quantum dot composition and remove the supernatant. Toluene was then added to the precipitate to disperse it, ethanol was added again, the solution was centrifuged, the supernatant was removed, and the solution was redispersed in toluene to prepare a toluene dispersion of the quantum dot composition.

The internal quantum efficiency of the obtained toluene dispersion of the quantum dot composition was 82%. In addition, the obtained toluene dispersion of the quantum dot composition was irradiated with blue light of 450 nm wavelength using a blue LED light source (HL-36, manufactured by AS ONE Corporation) for 12 hours in an air atmosphere, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 80%.

Example 3
In a nitrogen atmosphere, 31 mg of hexadecylphosphonic acid (HDPA) was weighed into a 20 ml vial, and 5 ml of toluene and 1 ml of ethanol were added and stirred to prepare a hexadecylphosphonic acid solution.

Further, under a nitrogen atmosphere, 10 g of the 1.0 wt % InP/ZnSe/ZnS/ _ZrO2 octadecene dispersion obtained in Production Example 5 and 6 ml of the hexadecylphosphonic acid solution were added to the three-neck flask. Next, the flask was heated and stirred at 50° C. under reduced pressure, and degassed for 10 minutes.

The flask was then purged with nitrogen, heated to 150° C., and stirred for 3 h to obtain a HDPA-modified quantum dot composition for InP/ZnSe/ZnS/ZrO ₂ .

The resulting solution was cooled to room temperature, ethanol was added, and the solution was centrifuged to precipitate the quantum dot composition and remove the supernatant. Toluene was then added to the precipitate to disperse it, ethanol was added again, the solution was centrifuged, the supernatant was removed, and the solution was redispersed in toluene to prepare a toluene dispersion of the quantum dot composition.

The internal quantum efficiency of the obtained toluene dispersion of the quantum dot composition was 82%. In addition, the obtained toluene dispersion of the quantum dot composition was irradiated with blue light of 450 nm wavelength using a blue LED light source (HL-36, manufactured by AS ONE Corporation) for 12 hours in an air atmosphere, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 79%.

Example 4
In a nitrogen atmosphere, 31 mg of hexadecylphosphonic acid (HDPA) was weighed into a 20 ml vial, and 5 ml of toluene and 1 ml of ethanol were added and stirred to prepare a hexadecylphosphonic acid solution.

Further, under a nitrogen atmosphere, 10 g of the 1.0 wt % InP/ZnSe/ZnS/TiO ₂ octadecene dispersion obtained in Production Example 6 and 6 ml of the hexadecylphosphonic acid solution were added to the three-neck flask.

The flask was then heated and stirred at 50° C. under reduced pressure for 10 minutes to degas the mixture, then purged with nitrogen, heated to 150° C., and stirred for 3 hours to obtain a quantum dot composition modified with HDPA for InP/ZnSe/ZnS/TiO ₂ .

The resulting solution was cooled to room temperature, ethanol was added, and the solution was centrifuged to precipitate the quantum dot composition and remove the supernatant. Toluene was then added to the precipitate to disperse it, ethanol was added again, the solution was centrifuged, the supernatant was removed, and the solution was redispersed in toluene to prepare a toluene dispersion of the quantum dot composition.

The internal quantum efficiency of the obtained toluene dispersion of the quantum dot composition was 78%. In addition, the obtained toluene dispersion of the quantum dot composition was irradiated with blue light of 450 nm wavelength using a blue LED light source (HL-36, manufactured by AS ONE Corporation) for 12 hours in an air atmosphere, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 77%.

Example 5
In a nitrogen atmosphere, 31 mg of hexadecylphosphonic acid (HDPA) was weighed into a 20 ml vial, and 5 ml of toluene and 1 ml of ethanol were added and stirred to prepare a hexadecylphosphonic acid solution.

Further, under a nitrogen atmosphere, 10 g of the 1.0 wt % AgInS ₂ /ZnS/Al ₂ O ₃ octadecene dispersion obtained in Production Example 7 and 6 ml of the hexadecylphosphonic acid solution were added to the three-neck flask.

The flask was then heated and stirred at 50° C. under reduced pressure for 10 minutes to degas the mixture, then purged with nitrogen, heated to 150° C., and stirred for 3 hours to obtain a quantum dot composition modified with HDPA for AgInS ₂ /ZnS/Al ₂ O ₃ .

The resulting solution was cooled to room temperature, ethanol was added, and the solution was centrifuged to precipitate the quantum dot composition and remove the supernatant. Toluene was then added to the precipitate to disperse it, ethanol was added again, the solution was centrifuged, the supernatant was removed, and the solution was redispersed in toluene to prepare a toluene dispersion of the quantum dot composition.

The internal quantum efficiency of the obtained toluene dispersion of the quantum dot composition was 63%. In addition, the obtained toluene dispersion of the quantum dot composition was irradiated with blue light of 450 nm wavelength using a blue LED light source (HL-36, manufactured by AS ONE Corporation) for 12 hours in an air atmosphere, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 61%.

Example 6
In a nitrogen atmosphere, 31 mg of hexadecylphosphonic acid (HDPA) was weighed into a 20 ml vial, and 5 ml of toluene and 1 ml of ethanol were added and stirred to prepare a hexadecylphosphonic acid solution.

Further, under a nitrogen atmosphere, 10 g of the 1.0 wt % AgInS ₂ /ZnS/ZrO ₂ octadecene dispersion obtained in Production Example 8 and 6 ml of the hexadecylphosphonic acid solution were added to the three-neck flask.

The flask was then heated and stirred at 50° C. under reduced pressure for 10 minutes to degas the mixture, then purged with nitrogen, heated to 150° C., and stirred for 3 hours to obtain a quantum dot composition modified with HDPA for AgInS ₂ /ZnS/ZrO ₂ .

The resulting solution was cooled to room temperature, ethanol was added, and the solution was centrifuged to precipitate the quantum dot composition and remove the supernatant. Toluene was then added to the precipitate to disperse it, ethanol was added again, the solution was centrifuged, the supernatant was removed, and the solution was redispersed in toluene to prepare a toluene dispersion of the quantum dot composition.

The internal quantum efficiency of the obtained toluene dispersion of the quantum dot composition was 65%. In addition, the obtained toluene dispersion of the quantum dot composition was irradiated with blue light of 450 nm wavelength using a blue LED light source (HL-36, manufactured by AS ONE Corporation) for 12 hours in an air atmosphere, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 62%.

(Example 7)
In a nitrogen atmosphere, 25 mg of dodecylphosphonic acid (DDPA) was weighed into a 20 ml vial, and 5 ml of toluene and 1 ml of ethanol were added and stirred to prepare a dodecylphosphonic acid solution.

Further, under a nitrogen atmosphere, 10 g of the 1.0 wt % InP/ZnSe/ZnS/Al ₂ O ₃ octadecene dispersion obtained in Production Example 4 and 6 ml of the dodecylphosphonic acid solution were added to the three-neck flask.

The flask was then heated and stirred at 50° C. under reduced pressure for 10 minutes to degas the mixture, then purged with nitrogen, heated to 150° C., and stirred for 3 hours to obtain a quantum dot composition modified with DDPA for InP/ZnSe/ZnS/Al ₂ O ₃ .

The resulting solution was cooled to room temperature, ethanol was added, and the solution was centrifuged to precipitate the quantum dot composition and remove the supernatant. Toluene was then added to the precipitate to disperse it, ethanol was added again, the solution was centrifuged, the supernatant was removed, and the solution was redispersed in toluene to prepare a toluene dispersion of the quantum dot composition.

The internal quantum efficiency of the obtained toluene dispersion of the quantum dot composition was 82%. In addition, the obtained toluene dispersion of the quantum dot composition was irradiated with blue light of 450 nm wavelength using a blue LED light source (HL-36, manufactured by AS ONE Corporation) for 12 hours in an air atmosphere, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 79%.

(Example 8)
In a nitrogen atmosphere, 22 mg of (4-bromobutyl)phosphonic acid (BBPA) was weighed into a 20 ml vial, and 5 ml of toluene and 1 ml of ethanol were added and stirred to prepare a (4-bromobutyl)phosphonic acid solution.

Further, under a nitrogen atmosphere, 10 g of the 1.0 wt % InP/ZnSe/ZnS/Al ₂ O ₃ octadecene dispersion obtained in Production Example 4 and 6 ml of the (4-bromobutyl)phosphonic acid solution were added to the three-neck flask.

The flask was then heated and stirred at 50° C. under reduced pressure for 10 minutes to degas the mixture, then purged with nitrogen, heated to 150° C., and stirred for 3 hours to obtain a quantum dot composition modified with BBPA for InP/ZnSe/ZnS/Al ₂ O ₃ .

The resulting solution was cooled to room temperature, ethanol was added, and the solution was centrifuged to precipitate the quantum dot composition and remove the supernatant. Toluene was then added to the precipitate to disperse it, ethanol was added again, the solution was centrifuged, the supernatant was removed, and the solution was redispersed in toluene to prepare a toluene dispersion of the quantum dot composition.

The internal quantum efficiency of the obtained toluene dispersion of the quantum dot composition was 81%. In addition, the obtained toluene dispersion of the quantum dot composition was irradiated with blue light of 450 nm wavelength using a blue LED light source (HL-36, manufactured by AS ONE Corporation) for 12 hours in an air atmosphere, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 78%.

(Example 9)
In a nitrogen atmosphere, 16 mg of phenylphosphonic acid (PhPA) was weighed into a 20 ml vial, and 5 ml of toluene and 1 ml of ethanol were added and stirred to prepare a phenylphosphonic acid (PhPA) solution.

Further, under a nitrogen atmosphere, 10 g of the octadecene dispersion of 1.0 wt % InP/ZnSe/ZnS/Al ₂ O ₃ obtained in Production Example 4 and 6 ml of the phenylphosphonic acid solution were added to the three-neck flask. Next, the flask was heated and stirred at 50° C. under reduced pressure, and degassed for 10 minutes.

The flask was then purged with nitrogen, heated to 150° C., and stirred for 3 hours to obtain a PhPA-modified quantum dot composition for InP/ZnSe/ZnS/Al ₂ O ₃ .

The resulting solution was cooled to room temperature, ethanol was added, and the solution was centrifuged to precipitate the quantum dot composition and remove the supernatant. Toluene was then added to the precipitate to disperse it, ethanol was added again, the solution was centrifuged, the supernatant was removed, and the solution was redispersed in toluene to prepare a toluene dispersion of the quantum dot composition.

The internal quantum efficiency of the obtained toluene dispersion of the quantum dot composition was 82%. In addition, the obtained toluene dispersion of the quantum dot composition was irradiated with blue light of 450 nm wavelength using a blue LED light source (HL-36, manufactured by AS ONE Corporation) for 12 hours in an air atmosphere, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 78%.

(Example 10)
In a nitrogen atmosphere, 25 mg of dodecylphosphonic acid (DDPA) was weighed into a 20 ml vial, and 5 ml of toluene and 1 ml of ethanol were added and stirred to prepare a dodecylphosphonic acid solution.

Further, under a nitrogen atmosphere, 10 g of the 1.0 wt % AgInS ₂ /ZnS/Al ₂ O ₃ octadecene dispersion obtained in Production Example 7 and 6 ml of the dodecylphosphonic acid solution were added to the three-neck flask.

The flask was then heated and stirred at 50° C. under reduced pressure for 10 minutes to degas the mixture, then purged with nitrogen, heated to 150° C., and stirred for 3 hours to obtain a quantum dot composition modified with DDPA for AgInS ₂ /ZnS/Al ₂ O ₃ .

The resulting solution was cooled to room temperature, ethanol was added, and the solution was centrifuged to precipitate the quantum dot composition and remove the supernatant. Toluene was then added to the precipitate to disperse it, ethanol was added again, the solution was centrifuged, the supernatant was removed, and the solution was redispersed in toluene to prepare a toluene dispersion of the quantum dot composition.

The internal quantum efficiency of the obtained toluene dispersion of the quantum dot composition was 63%. In addition, the obtained toluene dispersion of the quantum dot composition was irradiated with blue light of 450 nm wavelength using a blue LED light source (HL-36, manufactured by AS ONE Corporation) for 12 hours in an air atmosphere, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 60%.

Example 11
In a nitrogen atmosphere, 22 mg of (4-bromobutyl)phosphonic acid (BBPA) was weighed into a 20 ml vial, and 5 ml of toluene and 1 ml of ethanol were added and stirred to prepare a (4-bromobutyl)phosphonic acid solution.

Further, under a nitrogen atmosphere, 10 g of the 1.0 wt % AgInS ₂ /ZnS/Al ₂ O ₃ octadecene dispersion obtained in Production Example 7 and 6 ml of the (4-bromobutyl)phosphonic acid solution were added to the three-neck flask.

The flask was then heated and stirred at 50° C. under reduced pressure for 10 minutes to degas the mixture, then purged with nitrogen, heated to 150° C., and stirred for 3 hours to obtain a quantum dot composition modified with BBPA for AgInS ₂ /ZnS/Al ₂ O ₃ .

The resulting solution was cooled to room temperature, ethanol was added, and the solution was centrifuged to precipitate the quantum dot composition and remove the supernatant. Toluene was then added to the precipitate to disperse it, ethanol was added again, the solution was centrifuged, the supernatant was removed, and the solution was redispersed in toluene to prepare a toluene dispersion of the quantum dot composition.

The internal quantum efficiency of the obtained toluene dispersion of the quantum dot composition was 61%. In addition, the obtained toluene dispersion of the quantum dot composition was irradiated with blue light of 450 nm wavelength using a blue LED light source (HL-36, manufactured by AS ONE Corporation) for 12 hours in an air atmosphere, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 59%.

Example 12
In a nitrogen atmosphere, 22 mg of phenylphosphonic acid (PhPA) was weighed into a 20 ml vial, and 5 ml of toluene and 1 ml of ethanol were added and stirred to prepare a phenylphosphonic acid solution.

Further, under a nitrogen atmosphere, 10 g of the 1.0 wt % AgInS ₂ /ZnS/Al ₂ O ₃ octadecene dispersion obtained in Production Example 7 and 6 ml of the phenylphosphonic acid solution were added to the three-neck flask.

The flask was then heated and stirred at 50° C. under reduced pressure for 10 minutes to degas the mixture, then purged with nitrogen, heated to 150° C., and stirred for 3 hours to obtain a quantum dot composition modified with PhPA for AgInS ₂ /ZnS/Al ₂ O ₃ .

The resulting solution was cooled to room temperature, ethanol was added, and the solution was centrifuged to precipitate the quantum dot composition and remove the supernatant. Toluene was then added to the precipitate to disperse it, ethanol was added again, the solution was centrifuged, the supernatant was removed, and the solution was redispersed in toluene to prepare a toluene dispersion of the quantum dot composition.

The internal quantum efficiency of the obtained toluene dispersion of the quantum dot composition was 63%. In addition, the obtained toluene dispersion of the quantum dot composition was irradiated with blue light of 450 nm wavelength using a blue LED light source (HL-36, manufactured by AS ONE Corporation) for 12 hours in an air atmosphere, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 60%.

The above results are shown in Table 1.

Comparing the internal quantum yield values after blue light irradiation for the toluene dispersion of quantum dots in Production Example 1 and the toluene dispersion of quantum dots coated with metal oxides in Production Examples 3 to 6, and the toluene dispersion of quantum dot compositions coated with oxides and treated with phosphonic acid in Examples 1 to 4 and 7 to 9, it was shown that the quantum dot compositions in Examples 1 to 4 and 7 to 9 maintained higher internal quantum yield values.

In addition, when comparing the internal quantum yield values after blue light irradiation for the toluene dispersion of quantum dots from Production Example 2 and the toluene dispersion of quantum dots coated with metal oxides from Production Examples 7 and 8, and the toluene dispersion of the quantum dot compositions coated with oxides and treated with phosphonic acid from Examples 5, 6, and 10 to 12, it was shown that the quantum dot compositions from Examples 5, 6, and 10 to 12 maintained higher internal quantum yield values.

These results confirmed that quantum dots whose surfaces were modified with a metal oxide layer and phosphonic acid derivatives suppressed the decrease in internal quantum yield caused by blue light irradiation and improved photostability.

(Preparation of resin composition and wavelength converting material)
Example 13
A wavelength conversion material was produced using the quantum dot composition obtained in Example 1. 2.5 g of a 20 wt % toluene solution of the quantum dot composition was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being stirred and heated at 60°C.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength conversion material was 97 μm. The internal quantum efficiency of the obtained wavelength conversion material was 44%. The obtained wavelength conversion material was treated for 500 hours under conditions of 85°C and 85% RH (Relative Humidity), after which the fluorescence emission efficiency was measured and the internal quantum efficiency was found to be 41%.

(Example 14)
A wavelength conversion material was produced using the quantum dot composition obtained in Example 2. 2.5 g of a 20 wt % toluene solution of the quantum dot composition was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being stirred and heated at 60°C.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength converting material was 99 μm. The internal quantum efficiency of the obtained wavelength converting material was 47%. The fluorescence emission efficiency of the obtained wavelength converting material was measured after it was treated for 500 hours under conditions of 85°C and 85% RH, and the internal quantum efficiency was found to be 46%.

(Example 15)
A wavelength conversion material was produced using the quantum dot composition obtained in Example 3. 2.5 g of a 20 wt % toluene solution of the quantum dot composition was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being stirred and heated at 60°C.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength converting material was 99 μm. The internal quantum efficiency of the obtained wavelength converting material was 45%. The obtained wavelength converting material was treated for 500 hours under conditions of 85°C and 85% RH, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 44%.

(Example 16)
A wavelength conversion material was produced using the quantum dot composition obtained in Example 4. 2.5 g of a 20 wt % toluene solution of the quantum dot composition was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being stirred and heated at 60°C.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength converting material was 99 μm. The internal quantum efficiency of the obtained wavelength converting material was 43%. The obtained wavelength converting material was treated for 500 hours under conditions of 85°C and 85% RH, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 41%.

(Example 17)
A wavelength conversion material was produced using the quantum dot composition obtained in Example 5. 2.5 g of a 20 wt % toluene solution of the quantum dot composition was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being stirred and heated at 60°C.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength converting material was 98 μm. The internal quantum efficiency of the obtained wavelength converting material was 33%. The fluorescence emission efficiency of the obtained wavelength converting material was measured after it was treated for 500 hours under conditions of 85°C and 85% RH, and the internal quantum efficiency was found to be 32%.

(Example 18)
A wavelength conversion material was produced using the quantum dot composition obtained in Example 6. 2.5 g of a 20 wt % toluene solution of the quantum dot composition was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being stirred and heated at 60°C.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength converting material was 100 μm. The internal quantum efficiency of the obtained wavelength converting material was 32%. The obtained wavelength converting material was treated for 500 hours under conditions of 85°C and 85% RH, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 31%.

(Example 19)
A wavelength conversion material was produced using the quantum dot composition obtained in Example 7. 2.5 g of a 20 wt % toluene solution of the quantum dot composition was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being stirred and heated at 60°C.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength converting material was 99 μm. The internal quantum efficiency of the obtained wavelength converting material was 47%. The obtained wavelength converting material was treated for 500 hours under conditions of 85°C and 85% RH, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 45%.

(Example 20)
A wavelength conversion material was produced using the quantum dot composition obtained in Example 8. 2.5 g of a 20 wt % toluene solution of the quantum dot composition was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being stirred and heated at 60°C.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength converting material was 99 μm. The internal quantum efficiency of the obtained wavelength converting material was 45%. The obtained wavelength converting material was treated for 500 hours under conditions of 85°C and 85% RH, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 43%.

(Example 21)
A wavelength conversion material was produced using the quantum dot composition obtained in Example 9. 2.5 g of a 20 wt % toluene solution of the quantum dot composition was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being stirred and heated at 60°C.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength converting material was 98 μm. The internal quantum efficiency of the obtained wavelength converting material was 46%. The obtained wavelength converting material was treated for 500 hours under conditions of 85°C and 85% RH, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 45%.

(Example 22)
A wavelength conversion material was produced using the quantum dot composition obtained in Example 10. 2.5 g of a 20 wt % toluene solution of the quantum dot composition was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being stirred and heated at 60°C.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength converting material was 96 μm. The internal quantum efficiency of the obtained wavelength converting material was 33%. The fluorescence emission efficiency of the obtained wavelength converting material was measured after it was treated for 500 hours under conditions of 85°C and 85% RH, and the internal quantum efficiency was found to be 31%.

(Example 23)
A wavelength conversion material was produced using the quantum dot composition obtained in Example 11. 2.5 g of a 20 wt % toluene solution of the quantum dot composition was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being stirred and heated at 60°C.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength converting material was 99 μm. The internal quantum efficiency of the obtained wavelength converting material was 32%. The obtained wavelength converting material was treated for 500 hours under conditions of 85°C and 85% RH, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 30%.

(Example 24)
A wavelength conversion material was produced using the quantum dot composition obtained in Example 12. 2.5 g of a 20 wt % toluene solution of the quantum dot composition was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being stirred and heated at 60°C.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength converting material was 99 μm. The internal quantum efficiency of the obtained wavelength converting material was 33%. The obtained wavelength converting material was treated for 500 hours under conditions of 85°C and 85% RH, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 30%.

(Comparative Example 1)
A wavelength conversion material was produced using the quantum dots obtained in Production Example 1. 2.5 g of a 20 wt % toluene solution of the quantum dots was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being stirred and heated at 60°C.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength converting material was 96 μm. The internal quantum efficiency of the obtained wavelength converting material was 48%. The fluorescence emission efficiency of the obtained wavelength converting material was measured after it was treated for 500 hours under conditions of 85°C and 85% RH, and the internal quantum efficiency was found to be 27%.

(Comparative Example 2)
A wavelength conversion material was produced using the quantum dots obtained in Production Example 2. 2.5 g of a 20 wt % toluene solution of the quantum dots was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being heated at 60° C. with stirring.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength converting material was 98 μm. The internal quantum efficiency of the obtained wavelength converting material was 34%. The obtained wavelength converting material was treated for 500 hours under conditions of 85°C and 85% RH, after which the fluorescence emission efficiency was measured and the internal quantum efficiency was found to be 20%.

(Comparative Example 3)
A wavelength conversion material was produced using the oxide-coated quantum dots obtained in Production Example 3. 2.5 g of a 20 wt % toluene solution of the quantum dots was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being heated at 60° C. with stirring.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength converting material was 97 μm. The internal quantum efficiency of the obtained wavelength converting material was 44%. The obtained wavelength converting material was treated for 500 hours under conditions of 85°C and 85% RH, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 33%.

(Comparative Example 4)
A wavelength conversion material was produced using the oxide-coated quantum dots obtained in Production Example 4. 2.5 g of a 20 wt % toluene solution of the quantum dots was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being heated at 60° C. with stirring.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength converting material was 99 μm. The internal quantum efficiency of the obtained wavelength converting material was 47%. The fluorescence emission efficiency of the obtained wavelength converting material was measured after it was treated for 500 hours under conditions of 85°C and 85% RH, and the internal quantum efficiency was found to be 36%.

(Comparative Example 5)
A wavelength conversion material was produced using the oxide-coated quantum dots obtained in Production Example 5. 2.5 g of a 20 wt % toluene solution of the quantum dots was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being heated at 60° C. with stirring.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength converting material was 97 μm. The internal quantum efficiency of the obtained wavelength converting material was 46%. The fluorescence emission efficiency of the obtained wavelength converting material was measured after it was treated for 500 hours under conditions of 85°C and 85% RH, and the internal quantum efficiency was found to be 36%.

(Comparative Example 6)
A wavelength conversion material was produced using the oxide-coated quantum dots obtained in Production Example 6. 2.5 g of a 20 wt % toluene solution of the quantum dots was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being heated at 60° C. with stirring.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength converting material was 99 μm. The internal quantum efficiency of the obtained wavelength converting material was 42%. The obtained wavelength converting material was treated for 500 hours under conditions of 85°C and 85% RH, and the fluorescence emission efficiency was measured, resulting in an internal quantum efficiency of 34%.

(Comparative Example 7)
A wavelength conversion material was produced using the oxide-coated quantum dots obtained in Production Example 7. 2.5 g of a 20 wt % toluene solution of the quantum dots was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being heated at 60° C. with stirring.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength converting material was 100 μm. The internal quantum efficiency of the obtained wavelength converting material was 33%. The fluorescence emission efficiency of the obtained wavelength converting material was measured after it was treated for 500 hours under conditions of 85°C and 85% RH, and the internal quantum efficiency was found to be 23%.

(Comparative Example 8)
A wavelength conversion material was produced using the oxide-coated quantum dots obtained in Production Example 8. 2.5 g of a 20 wt % toluene solution of the quantum dots was mixed with 5.0 g of an acrylic resin (Acrydic BL-616-BA, manufactured by DIC Corporation), and the solvent was removed under reduced pressure while being stirred and heated at 60°C.

Then, the mixture was vacuum degassed and applied onto a 50 μm-thick polyethylene terephthalate (PET) film, and a resin composition layer was formed using a bar coater. A PET film was then attached onto this resin composition layer for lamination. This film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the resin composition layer and produce a wavelength converting material.

The thickness of the obtained wavelength converting material was 98 μm. The internal quantum efficiency of the obtained wavelength converting material was 32%. The fluorescence emission efficiency of the obtained wavelength converting material was measured after it was treated for 500 hours under conditions of 85°C and 85% RH, and the internal quantum efficiency was found to be 24%.

The above results are shown in Table 2.

The internal quantum efficiency values after 500 hours of treatment under conditions of 85°C and 85% RH were compared for the wavelength converting materials produced in Example 13 and Comparative Examples 1 and 3, Examples 14, 19 to 21 and Comparative Examples 1 and 4, Example 15 and Comparative Examples 1 and 5, Example 16 and Comparative Examples 1 and 6, Examples 17, 22 to 24 and Comparative Examples 2 and 7, and Example 18 and Comparative Examples 2 and 8. As a result, it was confirmed that the wavelength converting materials using the quantum dot composition of the present invention, which was surface-modified with a metal oxide layer and a phosphonic acid derivative in Examples 13 to 24, showed higher internal quantum efficiency values than quantum dots and quantum dots formed with only a metal oxide layer.

As described above, it has been confirmed that the quantum dot composition and resin composition using the quantum dot composition produced in the present invention, as well as the wavelength conversion material cured from the same, exhibit low degradation in fluorescence emission efficiency under high temperature and high humidity conditions, and are highly reliable, even when low-toxicity quantum dots are used.

（式（Ｉ）中、Ｒ_１は１つ以上の炭素原子を有する１価の有機基である。）
　［８］：前記ホスホン酸誘導体が、３－フェニル－２－プロペニルホスホン酸、テノホビル、２－ホスホノブタン－１，２，４－トリカルボン酸、４－ホスホノ安息香酸、ビニルホスホン酸、ｎ－オクチルホスホン酸、（３－ブロモプロピル）ホスホン酸、（４－ブロモブチル）ホスホン酸、（２－ブロモエチル）ホスホン酸、（４－ブロモフェニル）ホスホン酸、３－ホスホノプロピオン酸、（４－ヒドロキシフェニル）ホスホン酸、ヘキシルホスホン酸、４－ホスホノ酪酸、プロピルホスホン酸、（４－アミノベンジル）ホスホン酸、（４－アミノフェニル）ホスホン酸、３－ホスホノ安息香酸、メチルホスホン酸、ノニルホスホン酸、ベンズヒドリルホスホン酸、オクタデシルホスホン酸、（アミノメチル）ホスホン酸、（２－フェニルエチル）ホスホン酸、エチルホスホン酸、ブチルホスホン酸、デシルホスホン酸、ドデシルホスホン酸、（２－クロロエチル）ホスホン酸、４－メトキシフェニルホスホン酸、ヘキサデシルホスホン酸、（４－ヒドロキシベンジル）ホスホン酸、フェニルホスホン酸、（１Ｈ，１Ｈ，２Ｈ，２Ｈ－ヘプタデカフルオロデシル）ホスホン酸、テトラデシルホスホン酸、（１－アミノエチル）ホスホン酸、ウンデシルホスホン酸、ヘプチルホスホン酸、１０－カルボキシデシルホスホン酸、１１－アミノウンデシルホスホン酸・臭化水素酸塩、１１－ヒドロキシウンデシルホスホン酸、１Ｈ，１Ｈ，２Ｈ，２Ｈ－パーフルオロ－ｎ－ヘキシルホスホン酸、１Ｈ，１Ｈ，２Ｈ，２Ｈ－パーフルオロオクチルホスホン酸、１Ｈ，１Ｈ，２Ｈ，２Ｈ－パーフルオロ－ｎ－デシルホスホン酸、１１－｛２－［２－（２－メトキシエトキシ）エトキシ］エトキシ｝ウンデシルホスホン酸、１２－メルカプトデシルホスホン酸、及び［１１－（アクリロイルオキシ）ウンデシル］ホスホン酸から選択された１種以上のものであることを特徴とする上記［７］に記載の量子ドット組成物。
　［９］：前記ホスホン酸誘導体が、下記式（ＩＩ）で示されるものであることを特徴とする上記［１］～上記［６］のいずれかの量子ドット組成物。

（式（ＩＩ）中、Ｒ_２は１つ以上の炭素原子を有する２価の有機基である。）
　［１０］：前記ホスホン酸誘導体が、ｍ－キシリレンジホスホン酸、ｏ－キシリレンジホスホン酸、メチレンジホスホン酸、アレンドロン酸、１，４－ブチレンジホスホン酸、グリシン－Ｎ，Ｎ－ビス（メチレンホスホン酸）、ｐ－キシリレンジホスホン酸、ゾレドロン酸、１，３－プロピレンジホスホン酸、１，５－ペンチレンジホスホン酸、１，４－フェニレンジホスホン酸、１，２－エチレンジホスホン酸、１，６－ヘキシレンジホスホン酸、ミノドロナート、及び１－ヒドロキシエタン－１，１－ジホスホン酸から選択された１種以上のものであることを特徴とする上記［９］の量子ドット組成物。
　［１１］：前記ホスホン酸誘導体が、下記式（ＩＩＩ）で示されるものであることを特徴とする上記［１］～上記［６］のいずれかの量子ドット組成物。

（式（ＩＩＩ）中、Ｒ_３は１つ以上の炭素原子を有する３価の有機基である。）
　［１２］：前記ホスホン酸誘導体が、ニトリロトリス（メチレンホスホン酸）であることを特徴とする上記［１１］に記載の量子ドット組成物。
　［１３］：前記ホスホン酸誘導体が、下記式（ＩＶ）で示されるものであることを特徴とする上記［１］～上記［６］のいずれかの量子ドット組成物。

（式（ＩＶ）中、Ｒ_４は１つ以上の炭素原子を有する２価の有機基である。）
　［１４］：前記ホスホン酸誘導体がＮ，Ｎ，Ｎ’，Ｎ’－エチレンジアミンテトラキス（メチレンホスホン酸）であることを特徴とする上記［１３］に記載の量子ドット組成物。
　［１５］：前記Ｒ_１が、１個以上の炭素原子を有する直鎖もしくは分枝状のアルキル基、１個以上の炭素原子を有する直鎖もしくは分枝状のアルキレン基、アミノ基、カルボン酸基、エトキシ基、ブロモ基、クロロ基、フェノール基、パーフルオロアルキル基、水酸基、フェニル基、チオール基、アクリロイル基、及びオリゴエチレングリコール基のいずれかを少なくとも１種類以上含むものであることを特徴とする上記［７］に記載の量子ドット組成物。
　［１６］：前記Ｒ_２が、１個以上の炭素原子を有する直鎖もしくは分枝状のアルキル基、１個以上の炭素原子を有する直鎖もしくは分枝状のアルキレン基、アミノ基、カルボン酸基、エトキシ基、ブロモ基、クロロ基、フェノール基、パーフルオロアルキル基、水酸基、フェニル基、チオール基、アクリロイル基、及びオリゴエチレングリコール基のいずれかを少なくとも１種類以上含むものであることを特徴とする上記［９］に記載の量子ドット組成物。
　［１７］：前記Ｒ_３が、１個以上の炭素原子を有する直鎖もしくは分枝状のアルキル基、１個以上の炭素原子を有する直鎖もしくは分枝状のアルキレン基、アミノ基、カルボン酸基、エトキシ基、ブロモ基、クロロ基、フェノール基、パーフルオロアルキル基、水酸基、フェニル基、チオール基、アクリロイル基、及びオリゴエチレングリコール基のいずれかを少なくとも１種類以上含むものであることを特徴とする上記［１１］に記載の量子ドット組成物。
　［１８］：前記Ｒ_４が、１個以上の炭素原子を有する直鎖もしくは分枝状のアルキル基、１個以上の炭素原子を有する直鎖もしくは分枝状のアルキレン基、アミノ基、カルボン酸基、エトキシ基、ブロモ基、クロロ基、フェノール基、パーフルオロアルキル基、水酸基、フェニル基、チオール基、アクリロイル基、及びオリゴエチレングリコール基のいずれかを少なくとも１種類以上含むものであることを特徴とする上記［１３］に記載の量子ドット組成物。
　［１９］：上記［１］から上記［１８］のいずれかに記載の量子ドット組成物が樹脂中に分散されたものであることを特徴とする樹脂組成物。
　［２０］：前記樹脂は、エポキシ系樹脂、アクリル系樹脂、フッ素系樹脂、シリコーン系樹脂、カーボネート系樹脂、及びガラス樹脂から選択される少なくとも１種類以上のものであることを特徴とする上記［１９］に記載の樹脂組成物。
　［２１］：上記［２０］に記載の樹脂組成物の硬化物を含むものであることを特徴とする波長変換材料。 The present specification includes the following aspects.
[1]: A quantum dot composition comprising quantum dots that emit fluorescence when exposed to excitation light, the quantum dots comprising a semiconductor nanoparticle core and a semiconductor nanoparticle shell that do not contain Cd or Pb, the quantum dot surfaces being coated with a metal oxide, and the quantum dot surfaces or the metal oxide surfaces being modified with a phosphonic acid derivative.
[2]: The quantum dot composition according to [1] above, characterized in that the quantum dots are composed of the semiconductor nanoparticle core and a single or multiple semiconductor nanoparticle shells covering the semiconductor nanoparticle core.
[3]: The quantum dot composition according to [1] or [ ₂ ], characterized in that the _{semiconductor} nanoparticle core is selected from ZnS, ZnSe, ZnTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, _GaSb , InN, InP, InAs, InSb, _AgGaS2 , AgInS2, _AgGaSe2 , _AgInSe2 , _CuGaS2 , CuGaSe2, _CuInS2 , _CuInSe2 , _ZnSiP2 , and ZnGeP2 as a single, multiple, or mixed crystal.
[4]: The semiconductor nanoparticle core surface is made of GaCl ₃ , GaI ₃ , GaBr ₃ , ZnCl ₂ , ZnBr ₂ , ZnI ₂ , InCl ₃ , InBr ₃ , InI ₃ , AgCl, AgBr, AgI, KCl, KBr, KI, _NaCl , NaBr, NaI, MgCl ₂ , MgBr ₂ , MgI ₂ , CaCl 2 , CaBr ₂ , CaI ₂ , MnCl ₂ , MnBr ₂ , MnI ₂ , FeCl ₂ , FeBr ₂ , FeI ₂ , CuCl ₂ , CuBr ₂ , CuI ₂ , ZrCl ₄ , ZrBr ₄ , ZrI ₄ , GeCl ₄ , GeBr ₄ , and GeI _4.
[5]: The quantum dot composition according to any one of [1] to [4], characterized in that the semiconductor nanoparticle shell is selected from ZnS, ZnSe, ZnTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, and InSb as a single crystal, a plurality of crystals, or a mixed crystal.
[6]: A quantum dot composition according to any one of _{[ 1} ] to _{[ 5 ] above} , characterized in that _the metal oxide is at least one compound selected from _TiO2 , ZnO, _Al2O3 , _SiO2 , _ZrO2 , _Fe2O3 , MgO, _Y2O3 , _HfO2 , _CeO2 , _In2O3 , _{SnO2, WO3 , CrO3} , _Ta2O3 , BaTiO3, _V2O5 , NiO, NbO, _Cu2O , CuO, and MoO3 _.
[7]: The quantum dot composition according to any one of [1] to [6] above, wherein the phosphonic acid derivative is represented by the following formula (I):

(In formula (I), R ₁ is a monovalent organic group having one or more carbon atoms.)
[8]: The phosphonic acid derivative is 3-phenyl-2-propenylphosphonic acid, tenofovir, 2-phosphonobutane-1,2,4-tricarboxylic acid, 4-phosphonobenzoic acid, vinylphosphonic acid, n-octylphosphonic acid, (3-bromopropyl)phosphonic acid, (4-bromobutyl)phosphonic acid, (2-bromoethyl)phosphonic acid, (4-bromophenyl)phosphonic acid, 3-phosphonopropionic acid, (4-hydroxyphenyl)phosphonic acid, hexylphosphonic acid, acid, 4-phosphonobutyric acid, propylphosphonic acid, (4-aminobenzyl)phosphonic acid, (4-aminophenyl)phosphonic acid, 3-phosphonobenzoic acid, methylphosphonic acid, nonylphosphonic acid, benzhydrylphosphonic acid, octadecylphosphonic acid, (aminomethyl)phosphonic acid, (2-phenylethyl)phosphonic acid, ethylphosphonic acid, butylphosphonic acid, decylphosphonic acid, dodecylphosphonic acid, (2-chloroethyl)phosphonic acid, 4-methoxyphenyl Phosphonic acid, hexadecylphosphonic acid, (4-hydroxybenzyl)phosphonic acid, phenylphosphonic acid, (1H,1H,2H,2H-heptadecafluorodecyl)phosphonic acid, tetradecylphosphonic acid, (1-aminoethyl)phosphonic acid, undecylphosphonic acid, heptylphosphonic acid, 10-carboxydecylphosphonic acid, 11-aminoundecylphosphonic acid hydrobromide, 11-hydroxyundecylphosphonic acid, 1H,1H,2H,2H-perf The quantum dot composition according to the above [7], characterized in that it is one or more selected from the group consisting of perfluoro-n-hexylphosphonic acid, 1H,1H,2H,2H-perfluorooctylphosphonic acid, 1H,1H,2H,2H-perfluoro-n-decylphosphonic acid, 11-{2-[2-(2-methoxyethoxy)ethoxy]ethoxy}undecylphosphonic acid, 12-mercaptodecylphosphonic acid, and [11-(acryloyloxy)undecyl]phosphonic acid.
[9]: The quantum dot composition according to any one of [1] to [6], wherein the phosphonic acid derivative is represented by the following formula (II):

(In formula (II), _R2 is a divalent organic group having one or more carbon atoms.)
[10]: The quantum dot composition according to [9], characterized in that the phosphonic acid derivative is one or more selected from m-xylylene diphosphonic acid, o-xylylene diphosphonic acid, methylene diphosphonic acid, alendronic acid, 1,4-butylene diphosphonic acid, glycine-N,N-bis(methylene phosphonic acid), p-xylylene diphosphonic acid, zoledronic acid, 1,3-propylene diphosphonic acid, 1,5-pentylene diphosphonic acid, 1,4-phenylene diphosphonic acid, 1,2-ethylene diphosphonic acid, 1,6-hexylene diphosphonic acid, minodronate, and 1-hydroxyethane-1,1-diphosphonic acid.
[11]: The quantum dot composition according to any one of [1] to [6], wherein the phosphonic acid derivative is represented by the following formula (III):

(In formula (III), _R3 is a trivalent organic group having one or more carbon atoms.)
[12]: The quantum dot composition according to [11] above, characterized in that the phosphonic acid derivative is nitrilotris(methylene phosphonic acid).
[13]: The quantum dot composition according to any one of [1] to [6], wherein the phosphonic acid derivative is represented by the following formula (IV):

(In formula (IV), _R4 is a divalent organic group having one or more carbon atoms.)
[14]: The quantum dot composition according to [13] above, wherein the phosphonic acid derivative is N,N,N',N'-ethylenediaminetetrakis(methylenephosphonic acid).
[15]: The quantum dot composition according to the above [7], characterized in that R ₁ contains at least one of the following: a linear or branched alkyl group having one or more carbon atoms, a linear or branched alkylene group having one or more carbon atoms, an amino group, a carboxylic acid group, an ethoxy group, a bromo group, a chloro group, a phenol group, a perfluoroalkyl group, a hydroxyl group, a phenyl group, a thiol group, an acryloyl group, and an oligoethylene glycol group.
[16]: The quantum dot composition according to [9], wherein the R ₂ is at least one of a linear or branched alkyl group having one or more carbon atoms, a linear or branched alkylene group having one or more carbon atoms, an amino group, a carboxylic acid group, an ethoxy group, a bromo group, a chloro group, a phenol group, a perfluoroalkyl group, a hydroxyl group, a phenyl group, a thiol group, an acryloyl group, and an oligoethylene glycol group.
[17]: The quantum dot composition according to the above [11], characterized in that R ₃ contains at least one of the following: a linear or branched alkyl group having one or more carbon atoms, a linear or branched alkylene group having one or more carbon atoms, an amino group, a carboxylic acid group, an ethoxy group, a bromo group, a chloro group, a phenol group, a perfluoroalkyl group, a hydroxyl group, a phenyl group, a thiol group, an acryloyl group, and an oligoethylene glycol group.
[18]: The quantum dot composition according to the above [13], characterized in that R ₄ contains at least one of the following: a linear or branched alkyl group having one or more carbon atoms, a linear or branched alkylene group having one or more carbon atoms, an amino group, a carboxylic acid group, an ethoxy group, a bromo group, a chloro group, a phenol group, a perfluoroalkyl group, a hydroxyl group, a phenyl group, a thiol group, an acryloyl group, and an oligoethylene glycol group.
[19]: A resin composition comprising the quantum dot composition according to any one of [1] to [18] dispersed in a resin.
[20]: The resin composition according to [19] above, characterized in that the resin is at least one selected from the group consisting of epoxy resins, acrylic resins, fluorine-based resins, silicone resins, carbonate resins, and glass resins.
[21]: A wavelength converting material comprising a cured product of the resin composition according to [20] above.

The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included within the technical scope of the present invention.

Claims (21)

A quantum dot composition comprising quantum dots that emit fluorescence when excited by excitation light, the quantum dots being composed of a semiconductor nanoparticle core and a semiconductor nanoparticle shell that do not contain Cd or Pb, the quantum dot surface being coated with a metal oxide, and the quantum dot surface or the metal oxide surface being modified with a phosphonic acid derivative. The quantum dot composition according to claim 1, characterized in that the quantum dot is composed of the semiconductor nanoparticle core and one or more semiconductor nanoparticle shells covering the semiconductor nanoparticle core. _2. The quantum dot composition of claim 1, wherein the semiconductor nanoparticle core is selected from the group consisting of ZnS, ZnSe, ZnTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, _GaSb , InN, InP, InAs, InSb, AgGaS2, _AgInS2 , _AgGaSe2 , _AgInSe2 , _CuGaS2 , _CuGaSe2 , CuInS2, _CuInSe2 , _ZnSiP2 , and _ZnGeP2 as a single, multiple, or mixed crystal. The semiconductor nanoparticle core surface is made of GaCl ₃ , GaI ₃ , GaBr ₃ , ZnCl ₂ , ZnBr ₂ , ZnI ₂ , InCl ₃ , InBr ₃ , InI ₃ , AgCl, AgBr, AgI, KCl, KBr, KI, _NaCl , NaBr, NaI, MgCl ₂ , MgBr ₂ , MgI ₂ , CaCl 2 , CaBr ₂ , CaI ₂ , MnCl ₂ , MnBr ₂ , MnI ₂ , FeCl ₂ , FeBr ₂ , FeI ₂ , CuCl ₂ , CuBr ₂ , CuI ₂ , ZrCl ₄ , ZrBr ₄ , ZrI ₄ , GeCl ₄ , GeBr _2. The quantum dot composition according to claim 1, characterized in that it is passivated with one or more compounds selected from the group consisting of GeI4 and _GeI . The quantum dot composition according to claim 1, characterized in that the semiconductor nanoparticle shell is selected from ZnS, ZnSe, ZnTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, and InSb as a single crystal, multiple crystals, or mixed crystals. The quantum dot composition according to claim _{1 ,} characterized in that the metal oxide is at _{least one compound selected from TiO2, ZnO, Al2O3, SiO2, ZrO2, Fe2O3, MgO, Y2O3, HfO2, CeO2, In2O3, SnO2, WO3 , CrO3 , Ta2O3 , BaTiO3 , V2O5 , NiO , NbO , Cu2O , CuO , and MoO3 .} 2. The quantum dot composition according to claim 1, wherein the phosphonic acid derivative is represented by the following formula (I):

(In formula (I), R ₁ is a monovalent organic group having one or more carbon atoms.) The phosphonic acid derivative is 3-phenyl-2-propenylphosphonic acid, tenofovir, 2-phosphonobutane-1,2,4-tricarboxylic acid, 4-phosphonobenzoic acid, vinylphosphonic acid, n-octylphosphonic acid, (3-bromopropyl)phosphonic acid, (4-bromobutyl)phosphonic acid, (2-bromoethyl)phosphonic acid, (4-bromophenyl)phosphonic acid, 3-phosphonopropionic acid, (4-hydroxyphenyl)phosphonic acid, hexylphosphonic acid , 4-phosphonobutyric acid, propylphosphonic acid, (4-aminobenzyl)phosphonic acid, (4-aminophenyl)phosphonic acid, 3-phosphonobenzoic acid, methylphosphonic acid, nonylphosphonic acid, benzhydrylphosphonic acid, octadecylphosphonic acid, (aminomethyl)phosphonic acid, (2-phenylethyl)phosphonic acid, ethylphosphonic acid, butylphosphonic acid, decylphosphonic acid, dodecylphosphonic acid, (2-chloroethyl)phosphonic acid, 4-methoxyphenylphosphonic acid Sulfonic acid, hexadecylphosphonic acid, (4-hydroxybenzyl)phosphonic acid, phenylphosphonic acid, (1H,1H,2H,2H-heptadecafluorodecyl)phosphonic acid, tetradecylphosphonic acid, (1-aminoethyl)phosphonic acid, undecylphosphonic acid, heptylphosphonic acid, 10-carboxydecylphosphonic acid, 11-aminoundecylphosphonic acid hydrobromide, 11-hydroxyundecylphosphonic acid, 1H,1H,2H,2H-perfluoro The quantum dot composition according to claim 7, characterized in that it is one or more selected from the group consisting of perfluoro-n-hexylphosphonic acid, 1H,1H,2H,2H-perfluorooctylphosphonic acid, 1H,1H,2H,2H-perfluoro-n-decylphosphonic acid, 11-{2-[2-(2-methoxyethoxy)ethoxy]ethoxy}undecylphosphonic acid, 12-mercaptodecylphosphonic acid, and [11-(acryloyloxy)undecyl]phosphonic acid. The quantum dot composition according to claim 1, characterized in that the phosphonic acid derivative is represented by the following formula (II):

(In formula (II), _R2 is a divalent organic group having one or more carbon atoms.) The quantum dot composition according to claim 9, characterized in that the phosphonic acid derivative is one or more selected from m-xylylenediphosphonic acid, o-xylylenediphosphonic acid, methylenediphosphonic acid, alendronic acid, 1,4-butylenediphosphonic acid, glycine-N,N-bis(methylenephosphonic acid), p-xylylenediphosphonic acid, zoledronic acid, 1,3-propylenediphosphonic acid, 1,5-pentylenediphosphonic acid, 1,4-phenylenediphosphonic acid, 1,2-ethylenediphosphonic acid, 1,6-hexylenediphosphonic acid, minodronate, and 1-hydroxyethane-1,1-diphosphonic acid. The quantum dot composition according to claim 1, characterized in that the phosphonic acid derivative is represented by the following formula (III):

(In formula (III), _R3 is a trivalent organic group having one or more carbon atoms.) The quantum dot composition according to claim 11, characterized in that the phosphonic acid derivative is nitrilotris(methylene phosphonic acid). 2. The quantum dot composition according to claim 1, wherein the phosphonic acid derivative is represented by the following formula (IV):

(In formula (IV), _R4 is a divalent organic group having one or more carbon atoms.) The quantum dot composition according to claim 13, characterized in that the phosphonic acid derivative is N,N,N',N'-ethylenediaminetetrakis(methylenephosphonic acid). The quantum dot composition according to claim 7, characterized in that R ₁ contains at least one of the following: a linear or branched alkyl group having one or more carbon atoms, a linear or branched alkylene group having one or more carbon atoms, an amino group, a carboxylic acid group, an ethoxy group, a bromo group, a chloro group, a phenol group, a perfluoroalkyl group, a hydroxyl group, a phenyl group, a thiol group, an acryloyl group, and an oligoethylene glycol group. The quantum dot composition according to claim 9, characterized in that _R2 contains at least one of the following: a linear or branched alkyl group having one or more carbon atoms, a linear or branched alkylene group having one or more carbon atoms, an amino group, a carboxylic acid group, an ethoxy group, a bromo group, a chloro group, a phenol group, a perfluoroalkyl group, a hydroxyl group, a phenyl group, a thiol group, an acryloyl group, and an oligoethylene glycol group. The quantum dot composition according to claim 11, characterized in that _R3 contains at least one of the following: a linear or branched alkyl group having one or more carbon atoms, a linear or branched alkylene group having one or more carbon atoms, an amino group, a carboxylic acid group, an ethoxy group, a bromo group, a chloro group, a phenol group, a perfluoroalkyl group, a hydroxyl group, a phenyl group, a thiol group, an acryloyl group, and an oligoethylene glycol group. The quantum dot composition according to claim 13, characterized in that R ₄ contains at least one of the following: a linear or branched alkyl group having one or more carbon atoms, a linear or branched alkylene group having one or more carbon atoms, an amino group, a carboxylic acid group, an ethoxy group, a bromo group, a chloro group, a phenol group, a perfluoroalkyl group, a hydroxyl group, a phenyl group, a thiol group, an acryloyl group, and an oligoethylene glycol group. A resin composition comprising the quantum dot composition according to any one of claims 1 to 18 dispersed in a resin. The resin composition according to claim 19, characterized in that the resin is at least one selected from the group consisting of epoxy resins, acrylic resins, fluorine resins, silicone resins, carbonate resins, and glass resins. A wavelength converting material comprising a cured product of the resin composition according to claim 20.